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View Full Version : Stock cat vs. high flow cat



tontod
10-15-2006, 08:40 PM
Is a stock cat 600 cells? I have the techtonics HFC which I've been told is 400 cells. I'm wondering if I should go for an evoms HFC which is 200 cells. I dont want a testpipe for 2 reasons - smell and MA emissions. Would I see much of a gain/benefit? I have the borla 2.25" exhaust, have the PES T-28 kit.

CaSp3r9
10-15-2006, 09:07 PM
A stock cat is either 600 or 700 cell count, but I'm leaning towards 600... I don't know how strict MA emissions are but since a 200 cell count cat would more than likely throw a CEL, I don't think it would pass emissions but I could be wrong. As for power gains, I'm sure you'd see a little more, but it wouldn't be huge.

sean1.8t
10-15-2006, 10:01 PM
i've had my testpipe on for about 2 days now(not long at all). and i don't even see much of this smell everyone claims. just a little smell if you really try to notice it. but it isn't anything to gag over if you do smell it.. and it is a very well worth it mod. lots more power, lots less lagg. and it is defintately worth the extra $5 im going to have to grease the inspection guy with each year... so either keep your cat or go TP. another cat would be a lot of work for such a little difference in power. plus the 200 cell might not be MA emissions friendly either

onemoremile
10-15-2006, 10:04 PM
the test pipe and a good high flow cat have about the same power and performance gains. i had a labree test pipe and replaced it with a labree high flow cat and noticed no downside to the swap. i actually like the car a lot more with the high flow cat. i know i don't have to worry about a CEL, emissions laws, or deal with that damn droning. that test pipe was obnoxious. the HFC sound much nicer. The HFC was also much easier to install since i could get a wrench on all three top fasteners. the test pipe was a biatch to get on and off since the pipe was so close to the inside top bolt.

i had the test pipe for more than 6 months and ran it on the track (road course) and street. i also ran the HFC on the same track and noticed no drop in my lap times.

sean1.8t
10-15-2006, 10:07 PM
Originally posted by onemoremile
the test pipe and a good high flow cat have about the same power and performance gains. i had a labree test pipe and replaced it with a labree high flow cat and noticed no downside to the swap. i actually like the car a lot more with the high flow cat. i know i don't have to worry about a CEL, emissions laws, or deal with that damn droning. that test pipe was obnoxious. the HFC sound much nicer. The HFC was also much easier to install since i could get a wrench on all three top fasteners. the test pipe was a biatch to get on and off since the pipe was so close to the inside top bolt.

i had the test pipe for more than 6 months and ran it on the track (road course) and street. i also ran the HFC on the same track and noticed no drop in my lap times.

true dat yo!

onemoremile
10-15-2006, 10:41 PM
after having run both the test pipe and a hfc there is no way i would recommend a test pipe for street use. the only circumstance that i could see using a test pipe is in a full on race car that will use leaded fuel more often than not. on a street driven car the test pipe is more trouble than it is worth. the hfc is only about 50 bucks more anyway.

fred2ka4
10-15-2006, 11:03 PM
I really can't compare the two, since I have only had a high flow cat, but I will add this.

My high flow cat has performed very well, with no problems and the best part is when I took the car to get smogged, it passed with flying colors, BT and all! I don't know if that is possible with a test pipe so that is one less thing to have to worry about even if it is only once every two years. [:)] [up]

tontod
10-16-2006, 05:13 AM
Originally posted by onemoremile
the test pipe and a good high flow cat have about the same power and performance gains. i had a labree test pipe and replaced it with a labree high flow cat and noticed no downside to the swap. i actually like the car a lot more with the high flow cat. i know i don't have to worry about a CEL, emissions laws, or deal with that damn droning. that test pipe was obnoxious. the HFC sound much nicer. The HFC was also much easier to install since i could get a wrench on all three top fasteners. the test pipe was a biatch to get on and off since the pipe was so close to the inside top bolt.

i had the test pipe for more than 6 months and ran it on the track (road course) and street. i also ran the HFC on the same track and noticed no drop in my lap times.

I looked and the labree hfc is just $250, much cheaper than evoms. Is that 200 cells?

1 ate T
10-16-2006, 05:17 AM
TP is so controversial... you will never know what you will think of it off of someones opinion. It's truly an opinon of the person experiencing it. The gain is very noticeable, my car has a faint smell every now and then but is due to the hole I have in the flex joint DIRECTLY below me... which will of course billow in a little.

I'm enjoying it at the moment, and am having no problems. If you feel you will have problems, then don't try it... simply put.

Ray Khan
10-16-2006, 05:37 AM
tontod....where in MA are you? Definitely get the HFC for your T28. I have the APR kit and I've had the same experience with high flow cat and test pipe as onemoremile. Skip the test pipe. There aren't big gains to be had over the HFC. I couldn't stop the CEL from coming with the test pipe and therefore couldn't pass the computer part of inspection. It's definitely not woth the hassle. I dyno'd and ran the 1/4 mile with the HFC and test pipe and saw no gains on my car over the APR high flow cat. Good luck.

MR VTEC
10-16-2006, 06:15 AM
how much was the apr high flow...

tontod
10-16-2006, 07:40 AM
Originally posted by Ray Khan
tontod....where in MA are you? Definitely get the HFC for your T28. I have the APR kit and I've had the same experience with high flow cat and test pipe as onemoremile. Skip the test pipe. There aren't big gains to be had over the HFC. I couldn't stop the CEL from coming with the test pipe and therefore couldn't pass the computer part of inspection. It's definitely not woth the hassle. I dyno'd and ran the 1/4 mile with the HFC and test pipe and saw no gains on my car over the APR high flow cat. Good luck.

I live in Woburn. The question is which is the best HFC out there, I guess the ones with the fewest cells - 200? Labree seems to be the most inexpensive at $250?

onemoremile
10-16-2006, 08:08 AM
the labree works and is inexpensive so that is my vote. i heard that they changed the cat element to 300 cells and a different manufacturer. mine is a magnaflow/carsound. i assume this because it came in a magnaflow box.

EuroA4
10-16-2006, 09:47 AM
I've recently added a Tanrumwerks 400cell HFC (made by Fast Addictions using a Magnaflow core with custom tubing, bungs and flanges). For $240 it was one of the best mods I've done to the car. I feel the difference in spool time, and can notice nice torque gains. And it passed emissions, does not smell like gas, fit well and looks beautiful.

Ray Khan
10-16-2006, 10:32 AM
I'm in Melrose tontod....I must have seen your car around at some point. My APR one comes in the stage 3 kit, but I think it's on the order of $300-$400. I would go with one of those $250 options since the T28 uses an outlet adapter for a 3 bolt flange like stock. I've had a labree test pipe and the quality was very good. I'm sure their cat is just as nice.

fred2ka4
10-16-2006, 11:31 AM
Originally posted by MR VTEC
how much was the apr high flow...

The APR high flow cat cost $500, and it can only be used with the stage III or stage III+ kit, (as far as I know). I don't know if they make one for other or universal BT kits. I just like the fact that I passed smog! [:D]

The one thing I did like about the APR cat, was that when I called APR and told them I was going to smog the car and that the current programing that I was running, (WILD) had thrown a cell on my rear o2 sensor, (high flow reading) they sent me a new test pipe file that recalibrated my rear o2 sensor to read the higher rate of flow that was going through the cat. So they did it the right way and all was good. [up]

MR VTEC
10-16-2006, 11:51 AM
i have a gt28r dying to get in my car for over 2 yrs now. i also have a labree shotgun testpipe dying just as badly to make it's way into my car as well.
If i were stock or chipped i wouldn't worry about a high flow cat since the turbo is so small and spools so early.

b00st
10-16-2006, 02:30 PM
the scoop on HFCs...

i asked a friend from EVOMS about HFCs and this is what he told me......so i'd figure i'd share it.

400 is not really high flow, the highest I would go would be 200, anything more than that really isn’t going to yield good (any) performance gains. In fact putting a lesser quality 400 cell cat than the factory would be detrimental to power. Our cat is more like a 200 cell than a true 100 even though that is how it is listed in the catalogue, but I have never had any CEL issues with ours or Millteks. Milltek uses a HJS cat which you can do some research on, they are an European company. I didn’t mean that their systems are meant for bentley’s, just that they were viewed as qualified, where a lot of companies out there would have problems landing contracts with Yugo should they ever build cars again. I do a lot of cat replacement work here because of low quality units going bad. Most recently, last week, I replaced a cat that had a total bill with labor and parts of over $500 (VW application)…So that means that if he bought a $400 cat, then spent $150 to put it on, he has paid over $1000 for a HFC in the last year and a half… Spending $800 installed on a top notch one the first time suddenly seemed like a good investment to him ;) I am sure that GHL and Labree are good cats, and I don’t know anything about them like I said, I just really wish to encourage you to do some in depth research before you make a solid decision because I see A LOT of people go through a frustrating period that could have been easily avoided by spending a few extra bucks up front. I just don’t like when customers are unhappy, makes me loose sleep at night. I don’t know tooo much about cat fabrication, but I know that material used (% of precious metals), coating techniques and material, pattern of cells, amount of cells, and warranty are all questions you should be looking into. Most Milltek cats have a 3 point swirl pattern which is superior to a single point (99% of cats). A single swirl point can do several things such as cone out (destroying the cat, very common) get clogged, or begin breaking down. A tri-swirl pattern avoids all three of these, however is much more difficult and time consuming to achieve. HJS is also the ONLY company that uses the special coating and technique they do to coat their cats (with what I don’t know), but that is another feature that is not included by most. Just because a cat is labeled as metallic doesn’t mean it is… it could have a content of precious metals of such a small percentage if any just for the ability to market it as such. And finally cell count, make sure it is at highest 200…anything more than that is approaching STOCK! I don’t mean to turn down your business and I hope that you continue to come to us for advice and future upgrades, I just don’t happen to be in the best position to offer what you are currently requesting at reasonable prices, I’m just looking out for your best interest. Talk to you soon!

so take that for what its worth. some good info though.

bitterchild
10-16-2006, 02:34 PM
apr's stage 3 hfc is also a 3 pt swirl design

fred2ka4
10-16-2006, 04:11 PM
Originally posted by bitterchild
apr's stage 3 hfc is also a 3 pt swirl design

[:D]

GraysonF
10-16-2006, 04:22 PM
you wont notice the smell of a testpipe. it will give you the best gains, and for about 10 bucks, you dont have to worry about a CEL so you can pass inspection

48855
10-16-2006, 04:27 PM
Yea, what the cheapest HFC out there?

tontod
10-16-2006, 05:09 PM
Originally posted by gfanellia4
you wont notice the smell of a testpipe. it will give you the best gains, and for about 10 bucks, you dont have to worry about a CEL so you can pass inspection

I can get rid of the CEL with the anti fouler mod, but I wonder if they'll actually open the hood to look and see if I have a cat.

GraysonF
10-16-2006, 07:02 PM
no, they wont. and they dont care. cats look different from automobile to automobile. maybe an audi Cat looks like that shiny piece of silver?